JP2022104706A - Composite absorber and polymer absorbent - Google Patents

Abstract

To provide an absorber capable of stably exhibiting absorption performance.SOLUTION: A composite absorber (1) according to the present invention is for absorbing liquid, the composite absorber (1) comprising: a polymer absorbent having hydrophilic continuous skeletons and continuous pores; and a highly absorbent polymer. The polymer absorbent contains at least a -COOH group and a -COONa group as ion exchange groups, and the total ion exchange capacity of the -COOH group and the -COONa group per mass in a dry state is at least 4.0 mg eq/g.SELECTED DRAWING: Figure 4

Description

The present invention relates to a composite absorber and a polymer absorbent.

As an absorber used for absorbing a liquid such as an aqueous solution, one using a highly absorbent polymer (so-called "SAP") having a high liquid absorption amount is known.
For example, as disclosed in Patent Documents 1 to 5, various materials such as disposable disposable diapers, dew condensation prevention sheets, civil engineering / building materials such as simple soil, base materials such as pharmaceuticals, and materials for absorbing leaked liquids. It is applied to the field.

International Publication No. 2013/018571 Japanese Unexamined Patent Publication No. 2017-366638 JP-A-2017-205225 Japanese Unexamined Patent Publication No. 63-75016 Japanese Unexamined Patent Publication No. 8-38893

While such a highly absorbent polymer (SAP) can retain a large amount of liquid (that is, has a high liquid retention capacity), it has a slow liquid absorption rate, so that it is temporary in a conventional absorber. It is used in combination with pulp so that it can retain liquid quickly. In such a conventional absorber, when the liquid is discharged, the liquid is quickly absorbed by the pulp in the absorber, temporarily held in the pulp, and then handed over to SAP having a high liquid retention capacity. Will be held within.
On the other hand, the liquid to be absorbed by the absorber generally contains not a few ions, and in particular, the amount of divalent ions (for example, Ca ²⁺ , Mg ²⁺ , etc.) in the liquid is very small. Also has a great adverse effect on the absorption performance of the SAP (particularly, the amount of liquid absorbed, the amount of liquid retained, and the absorption rate).
However, since the conventional absorber does not have a function of modifying the salt concentration in the liquid, the liquid temporarily held in the pulp is transferred to the SAP as it is, and is in the liquid. Due to the influence of the salt concentration (particularly, the divalent ion concentration), the absorption performance of the SAP may vary, and as a result, the absorption performance of the absorber may not be stably exhibited.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an absorber capable of stably exhibiting absorption performance.

One aspect (aspect 1) of the present invention is a composite absorber for absorbing a liquid.
The composite absorber comprises a polymer absorbent having a hydrophilic continuous skeleton and continuous pores, and a highly absorbent polymer.
The polymer absorbent contains at least -COOH group and -COONa group as ion exchange groups, and the total ion exchange capacity of the -COOH group and -COONa group per mass in a dry state is 4.0 mg equivalent / The complex absorber, characterized in that it is g or more.

In the composite absorber of this embodiment, the polymer absorbent has a hydrophilic continuous skeleton and continuous pores, so that the liquid can be quickly absorbed and temporarily retained, and further, the ion exchange group can be used. By containing a certain amount of -COOH group and -COONa group or more, when the polymer absorbent absorbs the liquid and temporarily retains it, the ions in the liquid (particularly Ca ²⁺ , Mg ² ) Divalent ions such as ⁺ ) are exchanged by -COOH group and -COONa group, and the liquid is adversely affected by the absorption performance (particularly, the amount of liquid absorbed, the amount of liquid retained, and the absorption rate) of the highly absorbent polymer (SAP). Can be reformed into a liquid that is less likely to cause
As a result, in the composite absorber of this embodiment, since the liquid is modified with the polymer absorbent and then delivered to the SAP, the absorption performance of the SAP is less likely to vary, and the absorption performance as the absorber is stable. Can be demonstrated.

Further, in another aspect (aspect 2) of the present invention, in the composite absorber of the above aspect 1, the polymer absorbent is characterized in that the ion exchange rate of polyvalent ions is 50% or more.

In the composite absorber of this embodiment, the ion exchange rate of the polyvalent ion (ion having a divalent or higher valence) of the polymer absorbent is 50% or more, and the liquid can be more reliably modified, so that the absorption performance of the SAP is achieved. It is possible to make the variation less likely to occur, and it is possible to more stably exhibit the absorption performance as an absorber.

In still another aspect (aspect 3) of the present invention, in the composite absorber of the above aspect 1 or 2, the polymer absorbent has a liquid absorption amount of 30 g / g or more per unit mass. ..

In the composite absorber of this embodiment, the polymer absorbent has a liquid absorption amount of a certain level or more, and can absorb a larger amount of liquid and steadily reform the mixture. It can be made less likely to occur, and the absorption performance as an absorber can be more stably exhibited.

In still another aspect (aspect 4) of the present invention, in any of the composite absorbers of the above aspects 1 to 3, the polymer absorbent has a porosity of 85% or more per unit volume of the polymer absorbent. It is characterized by being.

In the composite absorber of this embodiment, the polymer absorbent has a porosity of a certain level or more, and can absorb more liquid and steadily reform the mixture, so that the absorption performance of the SAP varies more. It can be made difficult, and the absorption performance as an absorber can be more stably and satisfactorily exhibited.

In still another aspect (aspect 5) of the present invention, in any of the composite absorbers of the above aspects 1 to 4, the polymer absorbent is characterized in that the average diameter of the continuous pores is 1 μm to 1000 μm. And.

In the composite absorber of this embodiment, since the average diameter of the continuous pores of the polymer absorbent is within the above-mentioned specific range, the space (pores) for taking in the liquid of the polymer absorbent is less likely to be crushed, and more. It can have a high absorption rate and can stably exhibit excellent absorption performance.
In particular, when the porosity per unit volume of the polymer absorbent is 85% or more and the average diameter of the continuous pores is 1 μm to 1000 μm, the liquid should be absorbed and modified by more pores. Therefore, there is an advantage that more excellent ion exchange efficiency can be realized.

In still another aspect (aspect 6) of the present invention, in any of the complex absorbers of the above aspects 1 to 5, the polymer absorbent is a monolithic absorbent.

In the composite absorber of this embodiment, the polymer absorbent is a monolithic absorbent, which can quickly absorb the liquid and more steadily transfer the temporarily held liquid to the SAP. Further excellent absorption performance can be stably exhibited.

In still another aspect of the present invention (aspect 7), in any of the composite absorbers of aspects 1 to 6, the polymer absorbent is a (meth) acrylic acid ester and two or more in one molecule. It is characterized by being a hydrolyzate of a crosslinked polymer of a compound containing a vinyl group.

In the composite absorber of this embodiment, since the polymer absorbent has the above-mentioned specific configuration, the hydrophilic continuous skeleton is likely to be elongated and the continuous pores are likely to be expanded when the liquid is absorbed. The liquid can be taken into the continuous pores more quickly, and it can exhibit higher absorption performance as an absorber, and more liquid can be steadily modified, further increasing the variation in the absorption performance of SAP. It can be made less likely to occur.

In still another aspect (aspect 8) of the present invention, in any of the composite absorbers of the above aspects 1 to 7, the highly absorbent polymer is an acrylic acid-based highly absorbent polymer having cations on its surface. It is characterized by being.

Acrylic acid-based highly absorbent polymers (SAPs) with cations on the surface are particularly susceptible to adverse effects on the absorption performance (particularly, the amount of liquid absorbed, the amount of liquid retained, and the absorption rate) due to the ions in the liquid. Even when the composite absorber of this embodiment contains such a SAP, when the polymer absorbent absorbs the liquid and temporarily retains the liquid, the ions in the liquid are contained in the -COOH group and the -COONa group. Since the liquid can be reformed by exchanging ions, the absorption performance of the SAP is less likely to vary, and the absorption performance as an absorber can be stably exhibited.

Yet another aspect of the present invention (Aspect 9) is a polymer absorbent used with a highly absorbent polymer.
With a hydrophilic continuous skeleton and continuous pores,
It is characterized by containing at least -COOH group and -COONa group as an ion exchange group, and the total ion exchange capacity of the -COOH group and -COONa group per mass in a dry state is 4.0 mg equivalent / g or more. It is a polymer absorbent.

The polymer absorbent of this embodiment has a hydrophilic continuous skeleton and continuous pores, so that it can quickly absorb a liquid and temporarily retain it, and further, it is an ion exchange group-COOH group. By containing a certain amount or more of -COONa groups, when the polymer absorbent absorbs the liquid and temporarily retains it, the ions in the liquid (particularly Ca ²⁺ , Mg ²⁺ , etc. 2) The valent ion) is ion-exchanged by the -COOH group and the -COONa group, and the liquid is a liquid that does not easily adversely affect the absorption performance (particularly, the amount of liquid absorbed, the amount of liquid retained, and the absorption rate) of the highly absorbent polymer (SAP). Can be modified to.
As a result, the polymer absorbent of this embodiment is delivered to the SAP after the liquid is modified with the polymer absorbent, so that the absorption performance of the SAP is less likely to vary and the absorption performance as an absorber is stable. Can be demonstrated.

The present invention can provide an absorber capable of stably exhibiting absorption performance.

FIG. 1 is an exploded perspective view of the composite absorber 1 according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the composite absorber 1', which is another embodiment of the present invention. FIG. 3 is a diagram illustrating a manufacturing process of the absorbent A, which is an example of the polymer absorbent. FIG. 4 is an SEM photograph of the absorbent A at a magnification of 50 times. FIG. 5 is an SEM photograph of the absorbent A at a magnification of 100 times. FIG. 6 is an SEM photograph of the absorbent A at a magnification of 500 times. FIG. 7 is an SEM photograph of the absorbent A at a magnification of 1000 times. FIG. 8 is an SEM photograph of the absorbent A at a magnification of 1500 times. FIG. 9 is a graph showing the relationship between the monovalent and divalent ion concentrations in the liquid and the absorption performance of SAP (liquid absorption amount, liquid retention amount and absorption rate). FIG. 10 is a graph showing the effect of the absorbent A, which is an example of the polymer absorbent, on the divalent ion concentration in the liquid.

Hereinafter, a preferred embodiment of the present invention will be described in detail using the composite absorber 1 which is one embodiment.
In the present specification, unless otherwise specified, "an object placed on a horizontal plane in a deployed state (for example, a composite absorber, etc.) is viewed from the upper side in the vertical direction in the thickness direction of the object. Is simply called "planar view".

[Composite absorber]
FIG. 1 is an exploded perspective view of the composite absorber 1 according to an embodiment of the present invention.
The composite absorber 1 shown in FIG. 1 has a substantially rectangular outer shape in a plan view, and has a first holding sheet 2 forming a surface on one side of the composite absorber 1 in the thickness direction. , A liquid absorbent consisting of a second holding sheet 3 forming the other surface of the composite absorbent 1 and a mixture of the polymer absorbent 4 and the highly absorbent polymer 5 (SAP) located between these sheets. It is provided with a sex member as a basic configuration.

The liquid-absorbent member in the composite absorber 1 is a polymer absorbent 4 having a hydrophilic continuous skeleton and continuous pores located between the first holding sheet 2 and the second holding sheet 3. The highly absorbent polymer 5 is configured to be able to absorb and hold the liquid that has permeated through the first holding sheet 2.

Further, the above-mentioned polymer absorbent contains at least -COOH group and -COONa group as ion exchange groups, and the total ion exchange capacity of -COOH group and -COONa group per mass in a dry state is 4.0 mg. It has a peculiar ion exchange ability of equal amount / g or more.

Since the polymer absorbent has a hydrophilic continuous skeleton and continuous pores, the composite absorber 4 can quickly absorb and temporarily retain the liquid, and is an ion exchange group. By containing a certain amount or more of COOH group and -COONa group, when the polymer absorbent absorbs the liquid and temporarily retains it, the ions in the liquid (particularly Ca ²⁺ , Mg ²⁺ , etc.) (Divalent ion) is exchanged with -COOH group and -COONa group to reform the liquid into a liquid that does not adversely affect the absorption performance of SAP (particularly, the amount of liquid absorbed, the amount of liquid retained, and the absorption rate). be able to.
As a result, the composite absorber 4 can be delivered to the SAP after the liquid is modified with the polymer absorbent, so that the absorption performance of the SAP is less likely to vary and the absorption performance as the absorber is stably exhibited. can do.

In the present invention, the liquid-absorbent member is not limited to the embodiment of the composite absorber 1 of the above-described embodiment, and the liquid-absorbent member includes at least a polymer absorbent and SAP exhibiting the above-mentioned peculiar liquid-absorbing behavior. If it is contained, it may or may not contain other liquid-absorbing materials.

Further, in the present invention, the configuration of the composite absorber is not limited to the embodiment of the composite absorber 1 of the above-described embodiment, and the composite absorber is, for example, the composite absorption of another embodiment of the present invention shown in FIG. Even if the hydrophilic fiber sheet 6 is located between the first holding sheet 2 and the liquid-absorbent member (that is, the polymer absorbent 4 and the highly absorbent polymer 5) as in the body 1'. good.

In the present invention, the outer shape, various dimensions, basis weight, etc. of the composite absorber are not particularly limited as long as the effects of the present invention are not impaired, and any outer shape (for example, circular shape) according to various uses, usage modes, etc. , Oval shape, polygonal shape, hourglass shape, design shape, etc.), various dimensions, basis weight, etc. can be adopted.

Hereinafter, various constituent members of the composite absorber of the present invention will be described in more detail using the composite absorber 1 of the embodiment shown in FIG. 1 as an example.

(Holding sheet)
In the composite absorber 1 shown in FIG. 1, the first holding sheet 2 forming the surface on one side of the composite absorber 1 has a substantially rectangular outer shape similar to the outer shape of the composite absorber 1 in a plan view. It has a shape. The first holding sheet 2 is formed of a liquid-permeable sheet-like member capable of allowing the liquid supplied to the composite absorber 1 to permeate and be absorbed and held by the inner liquid-absorbing member. ..

The first holding sheet 2 has a slightly larger size as a whole than the liquid absorbing member arranged inside (that is, compared with the arrangement area of the liquid absorbing material such as the polymer absorbent 4). At the peripheral edge portion, the composite absorber 1 is bonded to the second holding sheet 3 located on the other side in the thickness direction by an arbitrary adhesive, heat fusion means, or the like.

On the other hand, the second holding sheet 3 forming the surface on the other side of the composite absorber 1 has a substantially rectangular outer shape similar to the outer shape of the composite absorber 1 in a plan view. The second holding sheet 3 is liquid impermeable, preventing liquids that were not absorbed or held by the inner liquid-absorbing member or liquid exuded from the liquid-absorbing member from leaking to the outside of the composite absorber 1. It is formed by a sheet-like member of.

In the present invention, each of the sheet-like members that can be used as the first holding sheet and the second holding sheet is not limited to that of the above-described embodiment, and the composite absorber of the present invention is the first holding sheet and the first holding sheet. At least one of the second holding sheets may be formed by a liquid-permeable sheet-like member. That is, in the composite absorbent of the present invention, one of the first holding sheet and the second holding sheet may be formed of a liquid-impermeable sheet-like member.

When a liquid-permeable sheet-shaped member is used as the holding sheet, the liquid-permeable sheet-shaped member is not particularly limited as long as the effect of the present invention is not impaired, and is arbitrary according to various uses, usage modes, and the like. A liquid-permeable sheet-like member can be adopted. Examples of such a liquid-permeable sheet-like member include non-woven fabrics such as hydrophilic air-through non-woven fabrics, spunbonded non-woven fabrics, and point-bonded non-woven fabrics, woven fabrics, knitted fabrics, and porous resin films.

Further, when a hydrophilic non-woven fabric, a woven fabric, a knitted fabric, or the like (hereinafter, these are collectively referred to as "fiber sheet") is used as the liquid-permeable sheet-like member, these fiber sheets have a single-layer structure. It may have a multilayer structure of two or more layers. The type of constituent fibers of the fiber sheet is not particularly limited, and examples thereof include hydrophilic fibers such as cellulosic fibers and thermoplastic resin fibers that have been subjected to a hydrophilization treatment. These fibers may be used alone or in combination of two or more types.

Examples of the cellulosic fiber that can be used as the constituent fiber of the fiber sheet include natural cellulosic fiber (for example, plant fiber such as cotton), regenerated cellulose fiber, purified cellulose fiber, semi-synthetic cellulose fiber and the like. Examples of the thermoplastic resin fibers that can be used as the constituent fibers of the fiber sheet include olefin resins such as polyethylene (PE) and polypropylene (PP), polyester resins such as polyethylene terephthalate (PET), and 6-nylon. Examples thereof include fibers made of known thermoplastic resins such as polyamide resins. These resins may be used alone or in combination of two or more kinds of resins.

Further, when a liquid-impermeable sheet-like member is used as the holding sheet, the liquid-impermeable sheet-like member is not particularly limited as long as the effect of the present invention is not impaired, and is suitable for various uses and usage modes. Any liquid-impermeable sheet-like member can be adopted. Examples of such a liquid-impermeable sheet-like member include various hydrophobic thermoplastic resin fibers (for example, polyolefin fibers such as PE and PP, polyester fibers such as PET, and core sheath type). Hydrophobic non-woven fabric formed of composite fibers, etc .; Perforated or non-perforated resin film formed of hydrophobic thermoplastic resin such as PE or PP; Laminated body in which the non-woven fabric is bonded to the resin film; SMS non-woven fabric Such as laminated non-woven fabrics and the like.

In the present invention, the outer shape, various dimensions, basis weight, etc. of the holding sheet are not particularly limited as long as the effects of the present invention are not impaired, and any outer shape (for example, circular shape, etc.) according to various uses, usage modes, etc. Oval shape, polygonal shape, hourglass shape, design shape, etc.), various dimensions, basis weight, etc. can be adopted.

(Liquid absorbing member)
In the composite absorbent 1 shown in FIG. 1, the liquid-absorbent member has a hydrophilic continuous skeleton and continuous pores located between the first holding sheet 2 and the second holding sheet 3 as described above. The polymer absorbent 4 and the highly absorbent polymer 5 are configured to be able to absorb and hold the liquid that has permeated through the first holding sheet 2.

In the composite absorber 1, the polymer absorbent 4 and the highly absorbent polymer 5 of the liquid-absorbing member are hot-melt type bonded to each of the above-mentioned first holding sheet 2 and second holding sheet 3. Although it is bonded by any adhesive such as an agent, the polymer absorbent may not be bonded to the holding sheet in the composite absorbent of the present invention.

In the present invention, the liquid-absorbent member is essential to include, as described above, a polymer absorbent having a hydrophilic continuous skeleton and continuous pores and having the above-mentioned unique ion exchange ability, and a highly absorbent polymer. It is included as an ingredient. Although the polymer absorbent will be described later, the super absorbent polymer is a powder or granule made of a super absorbent polymer such as a sodium acrylate copolymer known in the art, and is referred to as SAP (Super Absorbent Polymer). Is to be done.

The specific type of the highly absorbent polymer (SAP) is not particularly limited, but for example, acrylic acid-based SAP in which cations are present on the surface can be preferably used. Acrylic acid-based SAPs in which cations are present on the surface are particularly susceptible to adverse effects on the absorption performance (particularly, the amount of liquid absorbed, the amount of liquid retained, and the absorption rate) due to the ions in the liquid, but they are composite absorbers. In No. 4, even when such a SAP is contained, when the polymer absorbent absorbs the liquid and temporarily retains the liquid, the ions in the liquid are exchanged by the -COOH group and the -COONa group. Since the liquid can be modified, the absorption performance of the SAP is less likely to vary, and the absorption performance as an absorber can be stably exhibited.

In the present invention, the liquid-absorbent member located between the first holding sheet and the second holding sheet may contain only the above-mentioned polymer absorbent and SAP as the liquid-absorbing material. In addition to these, a liquid-absorbent material known in the art may be further contained. Examples of such a liquid-absorbent material include hydrophilic fibers, and more specifically, pulp fibers (for example, crushed pulp and the like), cellulosic fibers such as cotton, rayon, and acetate. ..

In the present invention, the outer shape of the liquid-absorbent member (the plan-view shape of the arrangement region of the liquid-absorbent material), various dimensions, the basis weight, etc. are not particularly limited as long as the effects of the present invention are not impaired, and are desired. Any external shape, various dimensions, basis weight, etc. can be adopted according to the liquid absorbency, flexibility, strength, and the like.

(Hydrophilic fiber sheet)
In the present invention, the composite absorber is, for example, as in the composite absorbent 1'of another embodiment shown in FIG. 2, the first holding sheet 2 and the liquid absorbent member (that is, the polymer absorbent 4 and the polymer absorbent 4). A hydrophilic fiber sheet 6 may be provided between the highly absorbent polymer 5).

In the present invention, the hydrophilic fiber sheet that can be used for the composite absorber is not particularly limited as long as the effect of the present invention is not impaired, and any hydrophilic fiber sheet according to various uses, usage modes and the like can be adopted. .. Examples of such hydrophilic fiber sheets include hydrophilic non-woven fabrics, woven fabrics, and knitted fabrics. The hydrophilic fiber sheet may have a single-layer structure or may have a multi-layer structure of two or more layers.

The type of constituent fibers of the hydrophilic fiber sheet is not particularly limited, and examples thereof include hydrophilic fibers such as cellulosic fibers and thermoplastic resin fibers that have been subjected to a hydrophilization treatment. These fibers may be used alone or in combination of two or more types.
Further, examples of the cellulosic fiber that can be used as the constituent fiber of the hydrophilic fiber sheet include natural cellulose fiber (for example, plant fiber such as cotton), regenerated cellulose fiber, purified cellulose fiber, semi-synthetic cellulose fiber and the like. .. Further, as the thermoplastic resin fiber that can be used as the constituent fiber of the hydrophilic fiber sheet, for example, known heat such as an olefin resin such as PE and PP, a polyester resin such as PET, and a polyamide resin such as 6-nylon. Examples include fibers made of a plastic resin. These resins may be used alone or in combination of two or more kinds of resins.

In the present invention, the outer shape, various dimensions, basis weight, etc. of the hydrophilic fiber sheet are not particularly limited as long as the effects of the present invention are not impaired, and any outer shape, various dimensions, etc. according to various uses, usage modes, etc. Basis weight etc. can be adopted.

Hereinafter, the polymer absorbent used in the composite absorber of the present invention will be described in more detail.
[Polymer absorbent]
In the present invention, the polymer absorbent has a hydrophilic continuous skeleton and continuous pores, contains at least -COOH groups and -COONa groups as ion exchange groups, and has -COOH groups and-per mass in a dry state. The total ion exchange capacity of the COONa group is not particularly limited as long as it has a unique ion exchange ability of 4.0 mg equivalent / g or more. Such a polymer absorbent is, for example, a hydrolyzate of a crosslinked polymer of two or more monomers containing at least (meth) acrylic acid ester, and has a high functional group having at least one hydrophilic group. Molecular compounds can be mentioned. More specifically, it is a hydrolyzate of a (meth) acrylic acid ester and a crosslinked polymer of a compound containing two or more vinyl groups in one molecule, and has at least -COOH group and -COONa group. Molecular compounds can be mentioned. Such a polymer absorbent is an organic porous body having at least one -COONa group in one molecule, and further has a -COOH group. -COONa groups are distributed substantially uniformly in the skeleton of the porous body.

When the polymer absorbent is a hydrolyzate of such a (meth) acrylic acid ester and a crosslinked polymer of a compound containing two or more vinyl groups in one molecule, as will be described later, an aqueous solution or the like may be used. When the liquid is absorbed, the hydrophilic continuous skeleton tends to expand (that is, expands easily), and the continuous pores also tend to expand, so that more liquid can be taken into the continuous pores more quickly. As a result, the composite absorber containing such a polymer absorbent can exhibit higher absorption performance as an absorber, and can steadily modify more liquid, so that the absorption performance of SAP can be improved. It is possible to further reduce the variation.

In the present specification, the (meth) acrylic acid ester means an acrylic acid ester or a methacrylic acid ester.

In a polymer absorbent formed by a hydrolyzate of a crosslinked polymer of such a (meth) acrylic acid ester and divinylbenzene, a continuous hydrophilicity is provided by an organic polymer having at least -COONa group and -COOH group. A skeleton is formed, and there are communication holes (continuous pores) between the skeletons that serve as a liquid absorption field.
Since the hydrolysis treatment changes the -COOR group (that is, the carboxylic acid ester group) of the crosslinked polymer to a -COONa group or a -COOH group (see FIG. 3), the polymer absorbent is -COOR. It may have a group.

The presence of -COOH and -COONa groups in the organic polymer forming a hydrophilic continuous skeleton and the total ion exchange capacity of -COOH and -COONa groups per mass in the dry state are determined by infrared spectroscopy and weak acidity. It can be confirmed by analysis by the quantification method of ion exchange groups.

Here, FIG. 3 is a diagram illustrating a manufacturing process of the absorbent A, which is an example of the polymer absorbent. In FIG. 3, the upper figure shows the constituent raw materials of the polymerization, the middle figure shows Monolith A which is a crosslinked polymer of (meth) acrylic acid ester and divinylbenzene, and the lower figure shows the hydrolysis and hydrolysis to Monolith A in the middle figure. The absorbent A obtained by the drying treatment is shown.

Hereinafter, the absorbent A formed by the hydrolyzate of the crosslinked polymer of (meth) acrylic acid ester and divinylbenzene, which is an example of the polymer absorbent, will be described.

The polymer absorbent is not limited to such a absorbent A, but is a hydrolyzate of a (meth) acrylic acid ester and a crosslinked polymer of a compound having two or more vinyl groups in one molecule, or , It may be a hydrolyzate of a crosslinked polymer of two or more kinds of monomers containing at least (meth) acrylic acid ester.
However, if the polymer absorbent is a monolithic absorbent, the liquid can be quickly absorbed and the liquid temporarily held in the polymer absorbent can be more steadily delivered to the SAP. A composite absorber containing such a polymer absorbent can stably exhibit even better absorption performance.

In the following description, "monolith A" is an organic porous body composed of a crosslinked polymer of (meth) acrylic acid ester and divinylbenzene before hydrolysis treatment, and is "monolithic organic porous". Sometimes referred to as "polymer".
Further, the "absorbent A" is a hydrolyzate of a crosslinked polymer (monolith A) of (meth) acrylic acid ester and divinylbenzene after being hydrolyzed and dried. In the following description, the absorbent A is in a dry state.

First, the structure of the absorbent A will be described.
The absorbent A has a hydrophilic continuous skeleton and continuous pores as described above. As shown in FIG. 3, the absorbent A, which is an organic polymer having a hydrophilic continuous skeleton, was obtained by cross-linking and polymerizing a (meth) acrylic acid ester as a polymerization monomer and divinylbenzene as a cross-linking monomer. It is obtained by further hydrolyzing the crosslinked polymer (Monolith A).

The organic polymer forming a hydrophilic continuous skeleton has an ethylene group polymerization residue (hereinafter referred to as “constituent unit X”) and a crosslinked polymerization residue of divinylbenzene (hereinafter referred to as “constituent unit Y”) as constituent units. ”) And.
Furthermore, the polymerization residue (constituent unit X) of the ethylene group in the organic polymer forming the hydrophilic continuous skeleton has both -COOH group and -COONa group produced by hydrolysis of the carboxylic acid ester group. .. When the polymerization monomer is a (meth) acrylic acid ester, the polymerization residue (constituent unit X) of the ethylene group has an —COONa group, a —COOH group and an ester group.

In the absorbent A, the ratio of the crosslinked polymerization residue (constituent unit Y) of divinylbenzene in the organic polymer forming the hydrophilic continuous skeleton is, for example, 0.1 to 30 mol% with respect to all the constituent units. , Preferably 0.1 to 20 mol%. For example, in the absorbent A using butyl methacrylate as a polymerization monomer and divinylbenzene as a cross-linking monomer, the ratio of the cross-linking polymerization residue (constituent unit Y) of divinylbenzene in the organic polymer forming a hydrophilic continuous skeleton. Is, for example, about 3%, preferably 0.1 to 10 mol%, and more preferably 0.3 to 8 mol% with respect to all the constituent units.
When the ratio of the crosslinked polymerization residue of divinylbenzene in the organic polymer forming the hydrophilic continuous skeleton is 0.1 mol% or more, the strength of the absorbent A is less likely to decrease, and this divinylbenzene is less likely to decrease. When the ratio of the crosslinked polymerization residue of the above is 30 mol% or less, the amount of the liquid to be absorbed is less likely to decrease.

Further, in the absorbent A, the organic polymer forming the hydrophilic continuous skeleton may be composed of only the constituent unit X and the constituent unit Y, or in addition to the constituent unit X and the constituent unit Y, It may have a structural unit other than the structural unit X and the structural unit Y, that is, a polymerization residue of a monomer other than the (meth) acrylic acid ester and divinylbenzene.

Examples of the constituent units other than the constituent unit X and the constituent unit Y include styrene, α-methylstyrene, vinyltoluene, vinylbenzyl chloride, glycidyl (meth) acrylate, isobutene, butadiene, isoprene, chloroprene, vinyl chloride, and bromide. Polymerization residues of monomers such as vinyl, vinylidene chloride, tetrafluoroethylene, (meth) acrylonitrile, vinyl acetate, ethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, trimethylolpropanetri (meth) acrylate Can be mentioned.

The ratio of the structural units other than the structural unit X and the structural unit Y in the organic polymer forming the hydrophilic continuous skeleton is, for example, 0 to 50 mol%, preferably 0 to 30 with respect to all the structural units. It is mol%.

Further, the absorbent A preferably has a hydrophilic continuous skeleton having a thickness of 0.1 to 100 μm. When the thickness of the hydrophilic continuous skeleton of the absorbent A is 0.1 μm or more, the spaces (pores) for taking in the liquid in the porous body are less likely to be crushed during absorption, and the amount of liquid absorbed is less likely to decrease. On the other hand, when the thickness of the hydrophilic continuous skeleton is 100 μm or less, an excellent absorption rate can be easily obtained.

Since the pore structure of the hydrophilic continuous skeleton of the absorbent A is an open cell structure, the thickness of the continuous skeleton is measured by using the skeleton cross section appearing on the test piece for electron microscope measurement as the evaluation point of the thickness. .. The continuous skeleton is often formed in a polygonal shape because it is formed at intervals between water (water droplets) that are removed by dehydration / drying treatment after hydrolysis. Therefore, the thickness of the continuous skeleton is the average value of the diameters (μm) of the circles circumscribing the polygonal cross section. Also, in rare cases, there may be a small hole in the polygon, in which case the circumscribed circle of the cross section of the polygon surrounding the small hole is measured.

Further, the absorbent A preferably has an average diameter of continuous pores of 1 μm to 1000 μm. When the average diameter of the continuous pores of the absorbent A is 1 μm or more, the space (pores) for taking in the liquid in the porous body is less likely to be crushed during absorption, and the absorption rate is less likely to decrease. On the other hand, when the average diameter of the continuous pores is 1000 μm or less, an excellent absorption rate can be easily obtained. Therefore, the composite absorber provided with such an absorbent A can stably exhibit excellent absorption performance.
In particular, when the porosity per unit volume of the polymer absorbent described later is 85% or more and the average diameter of the continuous pores is 1 μm to 1000 μm, the liquid is absorbed by more pores and modified. Since the quality can be improved, there is an advantage that better ion exchange efficiency can be realized.

The average diameter (μm) of the continuous pores of the absorbent A can be measured by the mercury intrusion method, and the maximum value of the pore distribution curve obtained by the mercury intrusion method is adopted. As the sample for measuring the average diameter of the continuous pores, a sample dried for 18 hours or more in a vacuum dryer set at a temperature of 50 ° C. is used regardless of the ionic form of the absorbent A. The final ultimate pressure is 0 Torr.

Here, FIG. 4 is an SEM photograph having a magnification of 50 times for the absorbent A, FIG. 5 is an SEM photograph having a magnification of 100 times for the absorbent A, and FIG. 6 is an SEM photograph having a magnification of 500 for the absorbent A. It is a double SEM photograph, FIG. 7 is an SEM photograph having a magnification of 1000 times for the absorbent A, and FIG. 8 is an SEM photograph having a magnification of 1500 times for the absorbent A.
The absorbent A shown in FIGS. 4 to 8 is an example of an absorbent having butyl methacrylate as a polymerization monomer and divinylbenzene as a cross-linking monomer, and each has a cubic structure of 2 mm square.

The absorbent A shown in FIGS. 4 to 8 has a large number of bubble-shaped macropores, and further has a portion where these bubble-shaped macropores overlap each other. The absorbent A has an open cell structure in which the overlapping portions of the macropores have a common opening (mesopore), that is, an open cell structure (continuous macropore structure).

The portion where the macropores overlap each other has a common opening (mesopore) having an average diameter of 1 to 1000 μm, preferably 10 to 200 μm, particularly preferably 20 to 100 μm in a dry state, and most of them have an open pore structure. It has become. When the average diameter of the mesopore in a dry state is 1 μm or more, the absorption rate of the liquid to be absorbed becomes better. On the other hand, when the average diameter of the mesopore in a dry state is 1000 μm or less, the absorbent A is less likely to become brittle.
It should be noted that the number of such macropores overlapped with each other is about 1 to 12 for one macropore, and about 3 to 10 for most macropores.

Further, since the absorbent A has such an open cell structure, the macropore group and the mesopore group can be uniformly formed, and the particle aggregation type as described in Japanese Patent Application Laid-Open No. 8-252579 etc. can be formed uniformly. Compared to the porous body, there is an advantage that the pore volume and the specific surface area can be significantly increased.

The total pore volume of the pores (pores) of the absorbent A is preferably 0.5 to 50 mL / g, more preferably 2 to 30 mL / g. When the total pore volume of the absorbent A is 0.5 mL / g or more, the space (vacancy) for taking in the liquid in the porous body is less likely to be crushed during absorption, and the amount of liquid absorbed and the absorption rate are less likely to decrease. Become. On the other hand, when the total pore volume of the absorbent A is 50 mL / g or less, the strength of the absorbent A is less likely to decrease.

The total pore volume can be measured by the mercury intrusion method. As the sample for measuring the total pore volume, a sample dried for 18 hours or more in a vacuum dryer set at a temperature of 50 ° C. is used regardless of the ionic form of the absorbent A. The final ultimate pressure is 0 Torr.

Hereinafter, the state of contact between the absorbent A and the liquid will be described, but the same applies to the case where the liquid comes into contact with the liquid-absorbing member or the composite absorber containing the absorbent A.

First, the continuous pores included in the absorbent A shown in FIGS. 4 to 8 are pores in which a plurality of pores (pores) communicate with each other, and a large number of pores are provided from the appearance. Can be visually recognized with the naked eye. When a liquid comes into contact with the absorbent A having such a large number of pores, the hydrophilic continuous skeleton first instantly takes up some of the liquid by osmotic pressure and elongates (ie, expands). This extension of the continuous skeleton occurs in almost all directions. As the outer shape of the absorbent A increases due to the elongation of the continuous skeleton during liquid absorption, the size of each pore of the absorbent A also increases. When the size of the vacancies is increased in this way, the volume inside the vacancies is increased, so that the amount of liquid that can be retained in the vacancies also increases. The absorbent A, which has been enlarged by absorbing a certain amount of liquid in this way, can further absorb a predetermined amount of liquid into the enlarged pores by the capillary phenomenon.

The liquid absorbed in the hydrophilic continuous skeleton of the absorbent A is difficult to be released from the continuous skeleton (that is, it is difficult to release the liquid), while the liquid absorbed in the continuous pores is easy to release. In the composite absorbent body, the liquid absorbed in the continuous pores is separated, transferred to the SAP having a high liquid retention capacity, and steadily held in the SAP.

Further, the amount of the liquid absorbed by the absorbent A is larger than that of the liquid absorbed in the hydrophilic continuous skeleton. Since most of the absorption of the liquid by the absorbent A is performed by retaining the liquid in the pores by capillarity, the porosity (that is, absorption) which is the ratio of the volume of the voids in the pores (total pore volume). The larger the volume of the voids in the pores relative to the unit volume of the agent A, the more liquid can be absorbed.

The porosity per unit volume of such a polymer absorbent is preferably 85% or more, and more preferably 90% or more. When the porosity per unit volume of the polymer absorbent is 85% or more, it is possible to absorb a larger amount of liquid and steadily reform it, so that it is possible to make it more difficult for the absorption performance of SAP to vary. .. As a result, the composite absorber containing such a polymer absorbent can more stably and satisfactorily exhibit the absorption performance as an absorber.

For example, the porosity of the absorbent A shown in FIGS. 4 to 8 described above is as follows.
First, the specific surface area of the absorbent A obtained by the mercury intrusion method is 400 m ² / g, and the pore volume is 15.5 mL / g. This pore volume of 15.5 mL / g means that the volume of the pores in 1 g of the absorbent A is 15.5 mL.
Here, assuming that the specific gravity of the absorbent A is 1 g / mL, the volume occupied by the pores in 1 g of the absorbent A, that is, the pore volume is 15.5 mL, and the volume of the absorbent A of 1 g. Becomes 1 mL.
Then, the total volume (volume) of 1 g of the absorbent A becomes 15.5 + 1 (mL), and the ratio of the pore volume thereof becomes the porosity. Therefore, the porosity of the absorbent A is 15.5 / (. 15.5 + 1) × 100 ≈ 94%.

In the present invention, the absorbent A having such a hydrophilic continuous skeleton and continuous pores, that is, the polymer absorbent is applied to the composite absorber in the form of particles, sheets, or the like.
Further, as described above, this polymer absorbent contains at least -COOH group and -COONa group as ion exchange groups, and has a total ion exchange capacity of -COOH group and -COONa group per mass in a dry state. Since it has a unique ion exchange ability of 4.0 mg equivalent / g or more, when the polymer absorbent absorbs the liquid and temporarily retains it, the ions in the liquid (particularly Ca ²⁺⁾ , Mg ²⁺ and other divalent ions) are ion-exchanged with -COOH groups and -COONa groups, and the liquid is absorbed by the highly absorbent polymer (SAP) (particularly, the amount of liquid absorbed, the amount of liquid retained, and the absorption rate). ) Can be modified into a liquid that does not have an adverse effect. Therefore, the composite absorber to which such a polymer absorbent is applied can be delivered to the SAP after the liquid is modified with the polymer absorbent, so that the absorption performance of the SAP is less likely to vary, and the absorber is less likely to vary. It is possible to stably demonstrate the absorption performance as.

Here, FIG. 9 is a graph showing the relationship between the monovalent and divalent ion concentrations in the liquid and the absorption performance of SAP (liquid absorption amount, liquid retention amount and absorption rate), and FIG. 10 is a graph showing a polymer. It is a graph which shows the influence which the absorbent A which is an example of an absorbent has on the divalent ion concentration in a liquid.

As shown in FIG. 9, it can be seen that the liquid absorption amount, the liquid retention amount, and the absorption rate of the SAP decrease as the monovalent and divalent ion concentrations in the liquid increase. In particular, it can be seen that the divalent ion concentration has a large effect on the absorption performance of SAP, and even if it is a small amount, the amount of liquid absorbed, the amount of liquid retained, and the absorption rate of SAP are greatly reduced.

In this way, the ion concentration in the liquid has a great adverse effect on the absorption performance of SAP, but since the ion concentration varies from liquid to liquid, the absorption performance of SAP also varies according to the variation. It will occur.

However, the absorbent A, which is an example of the present invention, contains at least -COOH group and -COONa group as ion exchange groups, and has a total ion exchange capacity of -COOH group and -COONa group per mass in a dry state. Since it has a peculiar ion exchange ability of 4.0 mg equivalent / g or more, as shown in FIG. 10, ions in the liquid (particularly divalent ions) are separated by -COOH group and -COONa group. Ion exchange can be carried out to significantly reduce the ion concentration in the liquid, that is, the liquid can be modified into a liquid that does not adversely affect the absorption performance of SAP.

The graph shown in FIG. 10 shows the rate of change in ion concentration before and after contact between the actual urine (actual urine A, B and C) of three humans having different divalent ion concentrations and the absorbent A (that is, that is). The ion exchange rate of the absorbent A) was measured as follows.
First, the divalent ion concentrations (mEq / L) of each of the three real urines A, B and C are measured using an ion meter (HORIBA Compact Calcium Ion Meter LAQUAtwin-Ca-11 manufactured by Horiba Advanced Techno Co., Ltd.). do. The measured ion concentration is defined as the ion concentration "before contact with the absorbent A".

Next, 0.2 g of the polymer absorbent (absorbent A) was added to a glass filter (climbing glass filter, model number: 0777-01-101, outer diameter x foot length (mm): φ7 x 80, filter diameter. : Φ20 mm, capacity: 30 mL, material: borosilicate glass, pore diameter: 100 to 120 μm), pour 30 mL of the actual urine, and measure the divalent ion concentration (mEq / L) of the obtained filtrate with the above ion meter. Is measured using. The measured ion concentration is defined as the ion concentration "after contact with the absorbent A".

Then, the amount of change in ion concentration (mEq / L) before and after the contact with the absorbent A is calculated by subtracting the ion concentration after the contact with the absorbent A from the ion concentration before the contact with the absorbent A, and further, before and after the contact with the absorbent A. By dividing the amount of change in ion concentration (mEq / L) of the above by the ion concentration before contact with the absorbent A and multiplying by 100, the rate of change (%) in the divalent ion concentration in each of the actual urine A, B and C. Is calculated.
All of the above measurements are performed under the conditions of a temperature of 25 ° C. and a humidity of 60%.

As described above, the absorbent A of the example of the present invention has the above-mentioned peculiar ion exchange ability which is not found in the conventional liquid-absorbent material, and can quickly absorb the liquid and temporarily retain it. Ions in the liquid (particularly divalent ions) can be exchanged to reform the liquid into a liquid that does not adversely affect the absorption performance of the SAP.
As a result, the composite absorber containing such an absorbent A (polymer absorbent) can be delivered to the SAP after the liquid is modified, so that the absorption performance of the SAP is less likely to vary, and the absorber is less likely to vary. It is possible to stably demonstrate the absorption performance as.

In the present invention, the total ion exchange capacity of the -COOH group and the -COONa group per mass in the dry state of the polymer absorbent is preferably 6.0 mg equivalent / g or more, and 8.0 mg equivalent / g. The above is more preferable.

In the present invention, the polymer absorber preferably has an ion exchange rate of polyvalent ions (that is, divalent or higher ions) of 50% or more. When the ion exchange rate of the multivalent ion of the polymer absorbent is 50% or more, the liquid can be reformed more reliably, so that the variation in the absorption performance of SAP can be made less likely to occur. Therefore, the composite absorber containing such a polymer absorbent can more stably exhibit the absorption performance as an absorber.
The ion exchange rate of the polyvalent ion of the polymer absorbent is more preferably 60% or more, further preferably 70% or more.
Here, the ion exchange rate of the polyvalent ion of the polymer absorbent can be measured by any measuring method such as ICP emission analysis method, IC analysis method, atomic absorbance analysis method, etc., for example, divalent ion. The ion exchange rate of can be measured as follows.

<Measurement method of ion exchange rate of divalent ions of polymer absorbent>
(1) Artificial urine is prepared by dissolving 200 g of urea, 80 g of sodium chloride, 8 g of magnesium sulfate, 3 g of calcium chloride and about 1 g of dye: Blue No. 1 in 10 L of ion-exchanged water.
(2) The divalent ion concentration (mEq / L) of the prepared artificial urine is measured using an ion meter (HORIBA Compact Calcium Ion Meter LAQUAtwin-Ca-11, manufactured by Horiba Advanced Techno Co., Ltd.). The measured ion concentration is defined as "ion concentration before contact with the polymer absorbent".
(3) 0.2 g of polymer absorbent, which is a sample for measurement, is used in a glass filter (climbing glass filter, model number: 0777-01-101, outer diameter x foot length (mm): φ7 x 80, filter. Put it in a diameter: φ20 mm, volume: 30 mL, material: borosilicate glass, pore diameter: 100 to 120 μm), pour 30 mL of the artificial urine, and adjust the divalent ion concentration (mEq / L) of the obtained filtrate to the above. Measure using an ion meter. The measured ion concentration is referred to as "ion concentration after contact with the polymer absorbent".
(4) The amount of change in ion concentration (mEq / L) before and after contact with the polymer absorber is calculated by subtracting the ion concentration after contact with the polymer absorber from the ion concentration before contact with the polymer absorber, and further, this high value is obtained. The rate of change in divalent ion concentration (%) is calculated by dividing the amount of change in ion concentration (mEq / L) before and after contact with the molecular absorber by the ion concentration before contact with the polymer absorbent and multiplying by 100. .. In the present specification, this "rate of change in divalent ion concentration (%)" is referred to as "divalent ion exchange rate of the polymer absorbent".
All of the above measurements are performed under the conditions of a temperature of 25 ° C. and a humidity of 60%.

When the sample for measurement (polymer absorbent) is recovered from the product and used, it can be obtained according to the following <method for recovering the sample for measurement (polymer absorbent)>.

<Method of recovering sample (polymer absorbent) for measurement>
(1) Peel off the surface sheet or the like from the product to expose the absorber.
(2) Drop the object to be measured (polymer absorbent) from the exposed absorber, and use tweezers or the like to use tweezers or the like to remove a substance other than the object to be measured (in the form of particles) (for example, pulp or synthetic resin fiber). And remove it.
(3) Using a microscope or a simple loupe as a magnifying observation means, collect the object to be measured using tweezers or the like while observing the difference from SAP at a magnification that can be recognized or the pores of the porous body at a magnification that can be visually recognized. .. The magnification of the simple loupe is not particularly limited as long as the pores of the porous body can be visually recognized, and examples thereof include a magnification of 25 to 50 times.
(4) The measurement object thus recovered is used as a sample for measurement in various measurement methods.

Further, in the present invention, the polymer absorbent preferably has a liquid absorption amount of 30 g / g or more per unit mass. When the polymer absorbent has a certain amount of liquid absorption or more, it can absorb more liquid and steadily reform it, so that the absorption performance of SAP is less likely to vary. Can be done. Therefore, the composite absorber containing such a polymer absorbent can more stably exhibit the absorption performance as an absorber.
The amount of liquid absorbed per unit mass of the polymer absorbent is more preferably 40 g / g or more, and further preferably 50 g / g or more.
Here, the amount of liquid absorbed per unit mass of the polymer absorbent can be measured as follows.

<Measuring method of liquid absorption per unit mass of polymer absorbent>
(1) Mesh bag obtained by cutting 1 g of a sample (polymer absorbent) for measurement into 10 cm squares (manufactured by NBC Meshtec Inc., N-NO255HD 115 (standard width: 115 cm, 255 mesh / 2.54 cm, opening:) Enclose in 57 μm, wire diameter: 43 μm, thickness: 75 μm)). The mass (g) of the mesh bag is measured in advance. When the sample for measurement (polymer absorbent) is recovered from the product and used, it can be obtained according to the above-mentioned <Method for recovering the sample for measurement (polymer absorbent)>.
(2) Immerse the mesh bag containing the sample in a 0.9% sodium chloride aqueous solution for 1 hour.
(3) The mass (g) after hanging the mesh bag for 5 minutes and draining it is measured.
(4) The amount of liquid absorbed by the sample (g) is calculated by subtracting the mass of the sample (= 1 g) and the total mass of the mesh bag from the mass of the mesh bag after draining measured in (3) above, and further this absorption. By dividing the amount of liquid by the mass of the sample (= 1 g), the amount of liquid absorbed (g / g) per unit mass of the sample (polymer absorbent) is obtained.
All of the above measurement methods are performed under the conditions of a temperature of 25 ° C. and a humidity of 60%.

Hereinafter, a method for producing such a polymer absorbent will be described in detail by taking the above-mentioned absorbent A as an example.

[Manufacturing method of polymer absorbent]
As shown in FIG. 3, the above-mentioned absorbent A can be obtained by undergoing a cross-linking polymerization step and a hydrolysis step. Hereinafter, each of these steps will be described.

(Crosslink polymerization step)
First, an oil-soluble monomer for cross-linking polymerization, a cross-linking monomer, a surfactant, water, and, if necessary, a polymerization initiator are mixed to obtain a water-in-oil emulsion. This water-in-oil emulsion is an emulsion in which the oil phase becomes a continuous phase and water droplets are dispersed therein.

Then, in the above-mentioned absorber A, as shown in the upper figure of FIG. 3, butyl methacrylate, which is a (meth) acrylic acid ester, is used as the oil-soluble monomer, and divinylbenzene is used as the crosslinkable monomer, and the surfactant is used. Crosslink polymerization is carried out using sorbitan monooleate as an activator and isobutyronitrile as a polymerization initiator to obtain monolith A.

Specifically, in the absorbent A, as shown in the upper figure of FIG. 3, first, 9.2 g of t-butyl methacrylate as an oil-soluble monomer and 0.28 g of divinylbenzene as a crosslinkable monomer were used. 1.0 g of sorbitan monooleate (hereinafter abbreviated as "SMO") as a surfactant and 0.4 g of 2,2'-azobis (isobutyronitrile) as a polymerization initiator are mixed and uniformly mixed. Dissolve in.
Next, a mixture of t-butyl methacrylate / divinylbenzene / SMO / 2,2'-azobis (isobutyronitrile) was added to 180 g of pure water, and a vacuum stirring defoaming mixer (EM), which is a planetary stirring device, was added. Stir under reduced pressure using (manufactured by E) to obtain a water-in-oil emulsion.

Further, this emulsion is immediately transferred to a reaction vessel, sealed, and polymerized at 60 ° C. for 24 hours under the static condition. After completion of the polymerization, the contents are taken out, extracted with methanol, and dried under reduced pressure to obtain Monolith A having a continuous macropore structure. As a result of observing the internal structure of the monolith A by SEM, the monolith A had an open cell structure and the thickness of the continuous skeleton was 5.4 μm. The average diameter of the continuous pores measured by the mercury intrusion method was 36.2 μm, and the total pore volume was 15.5 mL / g.

The content of divinylbenzene with respect to all the monomers is preferably 0.3 to 10 mol%, more preferably 0.3 to 5 mol%. Further, the ratio of divinylbenzene to the total of butyl methacrylate and divinylbenzene is preferably 0.1 to 10 mol%, more preferably 0.3 to 8 mol%. In the above-mentioned absorbent A, the ratio of butyl methacrylate to the total of butyl methacrylate and divinylbenzene is 97.0 mol%, and the ratio of divinylbenzene is 3.0 mol%.

The amount of the surfactant added can be set according to the type of the oil-soluble monomer and the size of the desired emulsion particles (macropores), and is about 2 to 70 with respect to the total amount of the oil-soluble monomer and the surfactant. It is preferably in the range of%.

In order to control the bubble shape and size of monolith A, alcohols such as methanol and stearyl alcohol; carboxylic acids such as stearic acid; hydrocarbons such as octane, dodecane and toluene; cyclic ethers such as tetrahydrofuran and dioxane are used. It may coexist in the polymerization system.

The mixing method for forming the water-in-oil emulsion is not particularly limited. For example, a method of mixing each component at once, an oil-soluble monomer, a surfactant, and an oil-soluble polymerization initiator, which are oil-soluble. Any mixing method such as a method in which the component and a water-soluble component such as water or a water-soluble polymerization initiator are separately and uniformly dissolved and then the respective components are mixed can be adopted.

Further, the mixing device for forming the emulsion is not particularly limited, and any device such as a normal mixer, homogenizer, or high-pressure homogenizer can be adopted depending on the desired emulsion particle size, and further, the object to be treated can be used. A so-called planetary stirrer or the like can also be used, in which an object is placed in a mixing container and the mixture is rotated while revolving around a revolving axis in an inclined state to stir and mix the object to be processed.

Further, the mixing conditions are not particularly limited, and the stirring rotation speed, stirring time, and the like can be arbitrarily set according to the desired emulsion particle size. In the above planetary agitator, water droplets in the W / O emulsion can be uniformly generated, and the average diameter thereof can be arbitrarily set in a wide range.

As the polymerization conditions of the water-in-oil emulsion, various conditions can be adopted depending on the type of the monomer and the initiator. For example, when azobisisobutyronitrile, benzoyl peroxide, potassium persulfate, etc. are used as the polymerization initiator, they should be polymerized by heating at a temperature of 30 to 100 ° C. for 1 to 48 hours in a sealed container under an inert atmosphere. When hydrogen peroxide-ferrous chloride, sodium persulfate-sodium acid sulfite, etc. are used as the polymerization initiator, the temperature is 0 to 30 ° C. for 1 to 48 hours in a sealed container under an inert atmosphere. It may be polymerized.

After completion of the polymerization, the unreacted monomer and the residual surfactant can be removed by taking out the contents and performing Soxhlet extraction with a solvent such as isopropanol to obtain the monolith A shown in the middle figure of FIG. ..

(Hydrolyzed step)
Subsequently, a step (hydrolysis step) of hydrolyzing the monolith A (crosslinked polymer) to obtain the absorbent A will be described.

First, monolith A is immersed in dichloroethane containing zinc bromide, stirred at 40 ° C. for 24 hours, and hydrolyzed by contacting it with methanol, 4% hydrochloric acid, 4% sodium hydroxide aqueous solution and water in this order. After that, it is dried to obtain a block-shaped absorbent A. Further, the block-shaped absorbent A is pulverized to a predetermined size to obtain a particulate absorbent A. The form of the absorbent A is not limited to particles, and may be formed into a sheet during or after drying, for example.

Further, the method for hydrolyzing Monolith A is not particularly limited, and various methods can be adopted. For example, aromatic solvents such as toluene and xylene, halogen solvents such as chloroform and dichloroethane, ether solvents such as tetrahydrofuran and isopropyl ether, amide solvents such as dimethylformamide and dimethylacetamide, and alcohol solvents such as methanol and ethanol. , A method of contacting with a strong base such as sodium hydroxide using a carboxylic acid solvent such as acetic acid or propionic acid or water as a solvent, or hydrohalogenate such as hydrochloric acid, sulfuric acid, nitric acid, trifluoroacetic acid, methanesulfonic acid. , P-solvented acid such as toluenesulfonic acid or Lewis acid such as zinc bromide, aluminum chloride, aluminum bromide, titanium chloride (IV), cerium chloride / sodium iodide, magnesium iodide, etc. Be done.

Further, among the polymerization raw materials of the organic polymer forming the hydrophilic continuous skeleton of the absorbent A, the (meth) acrylic acid ester is not particularly limited, but the (meth) acrylic acid has C1 to C10 (that is, the number of carbon atoms). Alkyl esters of 1 to 10) are preferable, and C4 (that is, 4 carbon atoms) alkyl esters of (meth) acrylic acid are particularly preferable.
Examples of the C4 alkyl ester of (meth) acrylic acid include (meth) acrylic acid t-butyl ester, (meth) acrylic acid n-butyl ester, and (meth) acrylic acid iso-butyl ester.

Further, the monomer used for the cross-linking polymerization may be only (meth) acrylic acid ester and divinylbenzene, and in addition to (meth) acrylic acid ester and divinylbenzene, other than (meth) acrylic acid ester and divinylbenzene. It may contain other monomers.
In the latter case, the other monomer is not particularly limited, but for example, styrene, α-methylstyrene, vinyltoluene, vinylbenzyl chloride, glycidyl (meth) acrylate, diethylhexyl (meth) acrylate, isobutene, butadiene, isobrene. , Chloroprene, vinyl chloride, vinyl bromide, vinylidene chloride, tetrafluoroethylene, (meth) acrylonitrile, vinyl acetate, ethylene glycol di (meth) acrylate, trimethylolpropanetri (meth) acrylate and the like.
The proportion of the monomers other than the (meth) acrylic acid ester and divinylbenzene in all the monomers used for the cross-linking polymerization is preferably 0 to 80 mol%, more preferably 0 to 50 mol%.

Further, the surfactant is not limited to the above-mentioned sorbitan monooleate, and may be any one that can form a water-in-oil (W / O) emulsion when the cross-linking polymerization monomer and water are mixed. .. Examples of such surfactants include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene group nonylphenyl ether, polyoxyethylene group stearyl ether, and polyoxyethylene group sorbitan. Nonionic surfactants such as monooleate, anionic surfactants such as potassium oleate, sodium dodecylbenzenesulfonate, sodium dioctyl sulfosuccinate, cationic surfactants such as distearyldimethylammonium chloride, lauryldimethylbetaine and the like. Androgynous surfactants can be mentioned. These surfactants may be used alone or in combination of two or more.

Further, as the polymerization initiator, a compound that generates radicals by heat and light irradiation is preferably used. Further, the polymerization initiator may be water-soluble or oil-soluble, and may be, for example, azobis (4-methoxy-2,4-dimethylvaleronitrile), azobisisobutyronitrile, azobisdimethylvaleronitrile, azobiscyclohexanenitrile, etc. Azobiscyclohexanecarbonitrile, azobis (2-methylpropionamidine) dihydrochloride, benzoyl peroxide, potassium persulfate, ammonium persulfate, hydrogen peroxide-ferrous chloride, sodium persulfate-sodium acid sulfite, tetramethylthium disulfide, etc. Can be mentioned. However, in some cases, the polymerization proceeds only by heating or light irradiation without adding the polymerization initiator, so that it is not necessary to add the polymerization initiator in such a system.

The composite absorber of the present invention is not particularly limited, but for example, it is a composite absorption in various fields such as a dew condensation prevention sheet, a civil engineering / building material such as simple soil, a base material such as a pharmaceutical product, and a material for absorbing leaked liquid. Can be applied to the body. Therefore, the liquid to be absorbed by the composite absorber is not particularly limited, and is, for example, water or an aqueous solution (for example, seawater), an acid (for example, hydrochloric acid, etc.), a base (for example, sodium hydroxide, etc.), an organic solvent (for example, sodium hydroxide, etc.). For example, alcohols such as methanol and ethanol, ketones such as acetone, ethers such as hydrochloric acid (THF) and 1,4-dioxane, N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), etc.) can be mentioned. Be done. In addition, these liquids may be a mixture of two or more kinds of liquids.

Further, the present invention is not limited to the above-described embodiments and the like, and can be appropriately combined, substituted, modified, etc. within a range not deviating from the object and purpose of the present invention. In this specification, the ordinal numbers such as "first" and "second" are for distinguishing the items to which the ordinal numbers are attached, and mean the order, priority, importance, etc. of each item. It's not something to do.

1 Composite absorber 2 First holding sheet 3 Second holding sheet 4 Polymer absorbent 5 Highly absorbent polymer (SAP)
6 Hydrophilic fiber sheet

Claims (9)

A complex absorber for absorbing liquids
The composite absorber comprises a polymer absorbent having a hydrophilic continuous skeleton and continuous pores, and a highly absorbent polymer.
The polymer absorbent contains at least -COOH group and -COONa group as ion exchange groups, and the total ion exchange capacity of the -COOH group and -COONa group per mass in a dry state is 4.0 mg equivalent / The composite absorber, characterized in that it is g or more. The composite absorbent according to claim 1, wherein the polymer absorbent has an ion exchange rate of polyvalent ions of 50% or more. The composite absorbent according to claim 1 or 2, wherein the polymer absorbent has a liquid absorption amount of 30 g / g or more per unit mass. The composite absorbent according to any one of claims 1 to 3, wherein the polymer absorbent has a porosity of 85% or more per unit volume of the polymer absorbent. The composite absorbent according to any one of claims 1 to 4, wherein the polymer absorbent has an average diameter of 1 μm to 1000 μm of the continuous pores. The composite absorbent according to any one of claims 1 to 5, wherein the polymer absorbent is a monolithic absorbent. The polymer absorbent is a hydrolyzate of a (meth) acrylic acid ester and a crosslinked polymer of a compound containing two or more vinyl groups in one molecule, according to claims 1 to 6. The complex absorber according to any one of the above. The composite absorbent according to any one of claims 1 to 7, wherein the highly absorbent polymer is an acrylic acid-based highly absorbent polymer having cations on its surface. A polymer absorbent used with highly absorbent polymers
With a hydrophilic continuous skeleton and continuous pores,
It is characterized by containing at least -COOH group and -COONa group as ion exchange groups, and the total ion exchange capacity of the -COOH group and -COONa group per mass in a dry state is 4.0 mg equivalent / g or more. Polymer absorbent.

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